Add examples to reference (#1076)

* Updated examples urls

* Added links to examples

* Updated docs generation script to include code examples

* Fixes

* Skip index api

* Fix link

* Fix url generation

* API generation

* Fix new line

* API generation

* Fix leftover

* API generation

docs/examples/index.asciidoc

@@ -7,6 +7,10 @@ Following you can find some examples on how to use the client.
 * Executing a <<bulk_examples,bulk>> request;
 * Executing a <<exists_examples,exists>> request;
 * Executing a <<get_examples,get>> request;
+* Executing a <<sql_query_examples,sql.query>> request;
+* Executing a <<update_examples,update>> request;
+* Executing a <<update_by_query_examples,update by query>> request;
+* Executing a <<reindex_examples,reindex>> request;
 * Use of the <<ignore_examples,ignore>> parameter;
 * Executing a <<msearch_examples,msearch>> request;
 * How do I <<scroll_examples,scroll>>?
@@ -26,3 +30,7 @@ include::search.asciidoc[]
 include::suggest.asciidoc[]
 include::transport.request.asciidoc[]
 include::typescript.asciidoc[]
+include::sql.query.asciidoc[]
+include::update.asciidoc[]
+include::update_by_query.asciidoc[]
+include::reindex.asciidoc[]

docs/examples/sql.query.asciidoc

@@ -0,0 +1,64 @@
+[[sql_query_examples]]
+== SQL
+
+Elasticsearch SQL is an X-Pack component that allows SQL-like queries to be executed in real-time against Elasticsearch. Whether using the REST interface, command-line or JDBC, any client can use SQL to search and aggregate data natively inside Elasticsearch. One can think of Elasticsearch SQL as a translator, one that understands both SQL and Elasticsearch and makes it easy to read and process data in real-time, at scale by leveraging Elasticsearch capabilities.
+
+In the following example we will search all the documents that has the field `house` equals to `stark`, log the result with the tabular view and then manipulate the result to obtain an object easy to navigate.
+
+[source,js]
+----
+'use strict'
+
+const { Client } = require('@elastic/elasticsearch')
+const client = new Client({ node: 'http://localhost:9200' })
+
+async function run () {
+  await client.index({
+    index: 'game-of-thrones',
+    body: {
+      character: 'Ned Stark',
+      quote: 'Winter is coming.',
+      house: 'stark'
+    }
+  })
+
+  await client.index({
+    index: 'game-of-thrones',
+    body: {
+      character: 'Arya Stark',
+      quote: 'A girl is Arya Stark of Winterfell. And I\'m going home.',
+      house: 'stark'
+    }
+  })
+
+  await client.index({
+    index: 'game-of-thrones',
+    refresh: true,
+    body: {
+      character: 'Tyrion Lannister',
+      quote: 'A Lannister always pays his debts.',
+      house: 'lannister'
+    }
+  })
+
+  const { body } = await client.sql.query({
+    body: {
+      query: "SELECT * FROM \"game-of-thrones\" WHERE house='stark'"
+    }
+  })
+
+  console.log(body)
+
+  const data = body.rows.map(row => {
+    const obj = {}
+    for (var i = 0; i < row.length; i++) {
+      obj[body.columns[i].name] = row[i]
+    }
+    return obj
+  })
+
+  console.log(data)
+}
+
+run().catch(console.log)
+----

docs/examples/update_by_query.asciidoc

@@ -0,0 +1,59 @@
+[[update_by_query_examples]]
+== Update By Query
+
+The simplest usage of _update_by_query just performs an update on every document in the index without changing the source. This is useful to pick up a new property or some other online mapping change.
+
+[source,js]
+---------
+'use strict'
+
+const { Client } = require('@elastic/elasticsearch')
+const client = new Client({ node: 'http://localhost:9200' })
+
+async function run () {
+  await client.index({
+    index: 'game-of-thrones',
+    body: {
+      character: 'Ned Stark',
+      quote: 'Winter is coming.'
+    }
+  })
+
+  await client.index({
+    index: 'game-of-thrones',
+    refresh: true,
+    body: {
+      character: 'Arya Stark',
+      quote: 'A girl is Arya Stark of Winterfell. And I\'m going home.'
+    }
+  })
+
+  await client.updateByQuery({
+    index: 'game-of-thrones',
+    refresh: true,
+    body: {
+      script: {
+        lang: 'painless',
+        source: 'ctx._source["house"] = "stark"'
+      },
+      query: {
+        match: {
+          character: 'stark'
+        }
+      }
+    }
+  })
+
+  const { body } = await client.search({
+    index: 'game-of-thrones',
+    body: {
+      query: { match_all: {} }
+    }
+  })
+
+  console.log(body.hits.hits)
+}
+
+run().catch(console.log)
+
+---------

scripts/utils/generateDocs.js

@@ -4,8 +4,14 @@
 
 'use strict'
 
+const { readdirSync } = require('fs')
+const { join } = require('path')
 const dedent = require('dedent')
 
+const codeExamples = readdirSync(join(__dirname, '..', '..', 'docs', 'examples'))
+  .map(file => file.slice(0, -9))
+  .filter(api => api !== 'index')
+
 function generateDocs (common, spec) {
   var doc = dedent`
   [[api-reference]]
@@ -67,7 +73,7 @@ function commonParameters (spec) {
   === Common parameters
   Parameters that are accepted by all API endpoints.
 
-  link:{ref}/common-options.html[Reference]
+  link:{ref}/common-options.html[Documentation]
   [cols=2*]
   |===\n`
   Object.keys(spec.params).forEach(key => {
@@ -170,7 +176,10 @@ function generateApiDoc (spec) {
   client.${camelify(name)}(${codeParameters.length > 0 ? `{\n    ${codeParameters}\n}` : ''})
   ----\n`
   if (documentationUrl) {
-    doc += `link:${documentationUrl}[Reference]\n`
+    doc += `link:${documentationUrl}[Documentation] +\n`
+  }
+  if (codeExamples.includes(name)) {
+    doc += `{jsclient}/${name.replace(/\./g, '_')}_examples.html[Code Example] +\n`
   }
 
   if (params.length !== 0) {